National Geographic has bent over backwards producing clear figures illustrating anatomy, physiology, and many processes. Like any serious subject, a one-pass read doesn't suffice. Thus, each chapter starts off with a hierarchical a learning plan:
-- a gorgeous picture with an illustrative paragraph designed to pique curiosity,
-- a learning plan detailing successively deep levels of understanding: section concepts, figures & their processes, and finally reading the text,
-- periodic questions encouraging timely review,
-- real-world scenarios inspiring future medical professionals with application of the current topic,
-- finally online content supplementing difficult/abstract concepts.
Having recently acquired my PhD in physics (with no life science since high school biology), this book seems to be as good an introduction as can be expected. The cell (chapter 3) was particularly difficult because of the simultaneous introduction of new nouns and verbs simultaneously; these multiple unknowns compound the difficulty -- think fixing a string of Christmas lights with two bad bulbs. In the future, a video-based introduction to cell organelles would be a pedagogically superior approach.